In a plant of the type here considered, it is customary to place the roving-laden bobbins at the preparatory stage on a carriage for transportation to an associated spinning machine. There, an operator will lift an oncoming bobbin out of the carriage and either position it directly on the guide rack, as a replacement for an exhausted active bobbin, or store it temporarily in an adjacent area. While the circulation of a bobbin-transporting carriage between a roving frame or flyer of the preparatory stage and a given spinning machine can be automatically controlled, the removal of the arriving replacement bobbins from the carriage and their assignment to a working position in need thereof--with or without interim storage--is still a labor-intensive operation and correspondingly uneconomical. Such roving bobbins can be quite heavy, in fact, weighing sometimes as much as 3.5 kg.
In commonly owned application Ser. No. 476,546, filed by me jointly with two others on Mar. 18, 1983, there has been disclosed a spinning machine associated with a carriage having retaining means for receiving the replacement bobbins to be transported; this carriage is arrested at a holding station near the path of a service unit of the type referred to above. The service unit has transfer means programmed to pick up one or more replacement bobbins at a time for the retaining means of the carriage for delivery to a storage area in the vicinity of the guide rack of the spinning machine. This mobile service unit--whose main function is that of tying broken yarns or blowing air, for example--carries out the previously manually performed tasks of taking replacement bobbins from a transporter and placing them in a storage area near the supply rack which is usually at an elevated location. The human operator is consequently relieved of the duty to lift these roving-laden bobbins and may only have to shift them from the storage area to a mandrel or other gripper on the rack after removing a spent active bobbin therefrom. The latter task may be performed manually even though, in principle, it could also be automated, e.g. with the aid of a donning and doffing mechanism similar to that described in commonly owned U.S. Pat. No. 3,370,441.
There are, however, spinning machines not equipped with such a mobile service unit for which a special transporter would have to be provided in order to carry out the transfer of replacement bobbins from the supply carriage to the vicinity of a working position.